A plasma process is an essential technique for manufacturing a semiconductor device. To meet a recent requirement for high integration and high speed of LSI, semiconductor devices forming the LSI are required to be further miniaturized.
In a capacitively coupled plasma processing apparatus and an inductively coupled plasma processing apparatus, however, electron temperature of generated plasma is high and a region having high plasma density is limited. For these reasons, it has been difficult to perform a plasma process capable of satisfying the requirement for further miniaturization of the semiconductor devices.
In this regard, in order to achieve high level of miniaturization, it is necessary to generate plasma having low electron density and high plasma density. To meet such a requirement, there has been proposed a plasma processing apparatus configured to generate surface wave plasma in a processing chamber by microwave and to perform a plasma process on a semiconductor wafer (see, for example, Patent Documents 1 and 2).
In Patent Documents 1 and 2, there is described a plasma processing apparatus configured to radiate a microwave into a processing chamber through a coaxial tube and generate surface wave plasma having low electron temperature and high plasma density by exciting a gas by electric field energy of the surface wave of the microwave.
Patent Document 1: Japanese Patent Laid-open Publication No. 2003-188103
Patent Document 2: Japanese Patent Laid-open Publication No. 2003-234327
In the plasma processing apparatus of Patent 1, however, in order to radiate the microwave into the processing chamber through the coaxial tube, a ceiling plate of the processing chamber has a structure in which a dielectric plate such as quartz is provided between the surface wave plasma and slots, and the gas is supplied into the processing chamber from a sidewall of the processing chamber. Since the gas is supplied from an outside of the ceiling plate, a gas flow may not be controlled, which makes it difficult to control the plasma effectively. Further, although it is described that the ceiling plate may be made of a conductor, a structure capable of radiating an electromagnetic wave into the processing chamber is not mentioned.